Process of producing positive chromatized colloid designs on plates for printing purposes.



PA'TENTED OCT. 13, 1903.

M. RUDOMETOPF. PROCESS OF PRODUCING POSITIVE GHROMATIZED COLLOID DESIGNS 0N PLATES FOR PRINTING PURPOSES.

APPLICATION FILED FEB. 24, 1903.

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UNirnn warns Patented October 13, 1903.

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MICHAEL RUDOMETOFF, OF GATTSOHINA, RUSSIA, AS S IGNOR TO FELIX VON BRESSENSDORF, OF LEIPZIG, GERMANY.

PROCESS OF PRODUCING POSll'lVE CHROMATlZl-ID COLLOID DESiGNS ON PLATES FORPRINTING PURPOSES.

SPEGIFIGATION forming part of Letters'Patent No. 71,278, dated October 13, 1903.

Application filed February 24, 1903.

To aZZ whom, it may concern.-

Be it known that 1, MICHAEL Rononnrorr, a subject of the Czar of Russia, residing at Gattschina, in the Govern ment of Petersburg, Russia, have invented certain new and useful Improvements in Processes of ProducingPositive Chromatized Colloid Designs on Plates for Printing Purposes; and 1 do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

The property of colloids of combining with chrome salts of the alkaline metals under the influence of light, which causes them to lose their solubility and capability of swelling in water, has been utilized to effect the transfer of photographic negatives to lithographic stones or to metallic plates. This has hitherto been accomplished by means of two different processes-viz.,either by a direct transfer or by an intermediate transfer to paper the colloids principally employed being gela: tin or albumen.

In order to render the present specification easily intelligible, reference is had to the accompanying drawings, in which similar numorals of reference denote similar parts throughout the several views.

Figures 1, 2, and 3 are diagrams representingcross-sections through the plates employed in the processes hitherto known, while Figs. 4., 5, 6, 7, and 8 are a series of diagrams showing the method of carrying out the present process, as hereinafter particularly described.

Referring first to Figs. 1 to 3, in order to effect the direct transfer the plate or stone is first coated with a thin layer of the chromatized colloid-such, for instance, as albumen-and is exposed to the light beneath the negative. The light thus passes through the transparent parts 1 2 3 of the negative, Fig. 1, and converts the layer 4. 5 6 thereunder of the chromaiized albumen into the insoluble condition. After the negative has been removed and color 7 applied to the whole sensitive layer, Fig. 2, the transfer is developed with water. During this process the surfaces 8, 9, 10, and 11, which had previously been protected against the light by the opaque portions of the negative, will be dissolved, and

Serial No. 144,817. (No specimens.)

thus removed, so that a positive representation consisting of black lines 4, 5, and 6, Fig. 3, will be obtained, which does not, however, lie directly on the plate 12, but on the layer of undissolved colloid 4t 5 6.

The second known process for transferring by means of paper is analogous to the abovedescribed one. The only difference is that the chromatized layer is not applied to the plate itself to which the transfers are to be applied, but to the paper, on which the picture is produced in the known manner from the negative. The whole paper, covered with the color or printers ink, is then developed with water, and a positive picture remains on the paper as this is attained in Fig. 3 by means of a direct transfer. I

The present process is carried out in the following manner and illustrated in Figs. 4: to 8: The paper 13, Fig. 4, covered with a layer of the chromatized colloid, such as albumen, is exposed beneath the negative. The parts 17 18 19 of the colloid layer lying underneath the translucent parts 14: 15 16 of the negative will be rendered insoluble. In order to transfer this copy to the stone or metal plate, it is moistened at the back, or if this cannot be advantageously donefor instance, in the interest of an exact register for the colors-the copy may be kept dry and the stone moistened with water, as illustrated in Fig. 5. The copy is then rolled or otherwise pressed onto the plate 20, to which it adheres, and then the paper is moistened at the back until the moisture penetrates the same and dissolves the albumen. This permits of the paper being removed from the plate 20, on which the parts 21, 22, 23, and 24 of the colloid layer will remain, which had previously been lying under the opaque parts of the negative -01. e., the parts lying between those parts which had been rendered insoluble viz., 17 18 19, as shown in Fig. 6. After the chromatized albumen thus transferred to the plate 20 has dried the whole plate is entirely covered with color, Fig. 7. If the plate thus prepared be washed with water, the albumen will dissolve and with the color on it will come off the plate, while only those parts will remain on the plate as a positive picture which were situated between the soluble al- 'bumen parts 21 22 23 24, and this layer of color 26 27 28 will lie directly on the plate or stone 20in contradistinction to the process described with reference to Figs. 1 to 3.

This present process or method of transfer renders it possible to apply the negative copy in a dry condition to the moistened plate or stone, which is of great importance in the interest of an exact register in chromolithographic work. In addition to this advantage retouching or toning-down of parts of the picture may be much more easily and conveniently carried out than has hitherto been the case, inasmuch as the stone or plate may be sprinkled with a solution of gum-arabic or albumen before the color is rolled on, and thus any desired part of the design may be toned down to any desired degree. In addi tion to this the cop may be touched up with a pen or brush (will; a solution of gum-arabic or albumen) before the color has been applied, and the color maybe added after the alterations havebeenallowed to dry. Thus corrections may be easily made which could hitherto only be effected with difficulty with the aid of a point or scraper.

' The present process differs from those previously mentioned in that the interstices between the lines of the drawing (negative) which consists of a soluble layer of the chromatized colloid are transferred to the plate or stone and not the lines (positive) of the drawing and that finally a positive is attained the color of which lies directly on the plate itself.

I claim as my invention- 1. The improved process for producing positive chromatized colloid designs on plates for printing purpose which consists first in producing a layer of chromatized colloid, secondly in superposing a negative on the said layer, thirdly in exposing the colloid layer to light through the negative, fourthly in trans .chromatized colloid,secondly in superposing a negative on said layer, thirdly in exposing the layer to lightv through the said negative, fourthly in causing the surface of the layer to adhere to the printing-surface and fifthly removing the backing and exposed parts from the printing-surface leaving the unexposed parts thereon, substantially as set forth.

3. The improved process for prod ucingpositive chromatized colloid designs on plates for printing purposes which consists first in coating a temporary backing with a layer of chromatized colloid, secondly in superposing a negative on said layer, thirdly in exposing the layer to light through the said negative, fourthly in applying the surface of the undeveloped design to a moistened printingsurface, fifthly washing off the backing from the design, sixthly applying the printing medium to the layer, and finally washing away the soluble parts, substantially as set forth. In witness whereof I have hereunto set my hand in presence of two witnesses.

MICHAEL RUDOMETOFF. Witnesses:

P. SURIUS, O. ZoPKn. 

